Biology subjects

Lazaro, J.

Publications and source records attributed to Lazaro, J..

5 recordsLinked to original sources

bioRxiv2024

Systematic analysis of protein stability associated with species-specific developmental tempo

Human embryonic development proceeds more slowly than in mice. The segmentation clock offers a tractable model to study interspecies differences in developmental tempo, as its oscillation period in human induced presomitic mesoderm (iPSM) cells is approximately twice that of mouse. While the core clock gene HES7 exhibits slower protein degradation in human cells, it remains unclear whether such cross-species differences in protein stability reflect a general principle. Here, we perform a dynamic SILAC-based proteomic analysis of [~]5,000 proteins in human and mouse iPSM, and we uncover a pervasive trend of slower protein degradation in human cells, regardless of subcellular localization or degradation pathways. Moreover, inhibition of glycolysis in mouse iPSM phenocopies the human protein stability profile, and modulation of protein stability alters the tempo of both the segmentation clock and cellular differentiation. Together, our findings establish protein stability, with pervasive differences across species, as a key mediator linking metabolism to developmental tempo.

developmental biology↗

bioRxiv2024

Metabolic activities are selective modulators for individual segmentation clock processes

A sequence of cellular and molecular processes unfolding during embryonic development prompts fundamental questions of how the tempo of multiple processes is coordinated and whether a common global modulator exists. The oscillation of the segmentation clock is a well-studied model of developmental tempo. While the clock period is known to scale with the kinetics of gene expression and degradation processes of the core clock gene Hes7 across mammalian species, how these key molecular processes are coordinated remains unclear. In this study, we investigated if metabolic activities act as a global modulator for the segmentation clock, finding that they are rather selective modulators. While several metabolic inhibitions extended the clock period, their effects on the key processes varied. Inhibition of glycolysis decelerated the protein degradation of Hes7 and extended the production delay but did not influence the intron delay. Electron transport chain inhibition extended Hes7 intron delay without influencing the other two processes. Combinations of distinct metabolic inhibitions exhibited synergistic effects. By contrast, temperature changes affected the clock period and all three key processes simultaneously. These results highlight the selective effects of metabolic activities on segmentation clock processes, hinting that their scaled kinetics across species may be achieved through combinations of multiple modulators.

developmental biology↗

bioRxiv2022

A stem cell zoo uncovers intracellular scaling of developmental tempo across mammals

Differential speeds in biochemical reactions have been proposed to be responsible for the differences in developmental tempo between mice and humans. However, the underlying mechanism controlling the species-specific kinetics remains to be determined. Using in vitro differentiation of pluripotent stem cells, we recapitulated the segmentation clocks of diverse mammalian species varying in body weight and taxa: marmoset, rabbit, cattle and rhinoceros. Together with the mouse and human, the segmentation clock periods of the six species did not scale with the animal body weight, but were rather grouped according to phylogeny. The biochemical kinetics of the core clock gene HES7 displayed clear scaling with the species-specific segmentation clock period. However, the cellular metabolic rates did not show an evident correlation. Instead, genes involving biochemical reactions showed an expression pattern that scales with the segmentation clock period. Altogether, our stem cell zoo uncovered general scaling laws governing species-specific developmental tempo.*

developmental biology↗

bioRxiv2020

Temporal patterning of the central nervous system by a shared transcription factor code

The molecular mechanisms that ensure the reproducible generation of neuronal diversity in the vertebrate nervous system are incompletely understood. Here we provide evidence of a temporal patterning program consisting of cohorts of transcription factors expressed in neurons generated at successive developmental timepoints. This program acts in parallel to spatial patterning, diversifying neurons throughout the nervous system and in neurons differentiated in-vitro from stem cells. We demonstrate the TGF{beta} signalling pathway controls the pace of the temporal program. Furthermore, targeted perturbation of components of the temporal program, Nfia and Nfib, reveals their requirement for the generation of late-born neuronal subtypes. Together, our results provide evidence for the existence of a previously unappreciated global temporal program of neuronal subtype identity and suggest that the integration of spatial and temporal patterning programs diversifies and organises neuronal subtypes in the vertebrate nervous system.

developmental biology↗

bioRxiv2018

Temporal Control of Transcription by Zelda in living Drosophila embryos

Abstract/introPioneer factors have the exquisite ability to engage their target sites at nucleosomal DNA, which leads to a local remodeling of chromatin and the establishment of a transcriptional competence. However, the direct impact of enhancer priming by pioneer factors on the temporal control of gene expression and on mitotic memory remains elusive. In Drosophila embryos, the maternally deposited activator Zelda (Zld) exhibits key pioneer factor properties and indeed regulates the awakening of the zygotic genome. The analysis of thousands of endogenous Zld bound regions in various genetic contexts, as well as the study of isolated synthetic enhancers with static approaches, led to the proposal that Zld could act as a quantitative developmental timer. Here we employ quantitative live imaging methods and mathematical modeling to directly test the effect of Zld on temporal coordination in gene activation and on mitotic memory. Using an automatic tracking software, we quantified the timing of activation in hundreds of nuclei and their progeny in Drosophila embryos. We demonstrate that increasing the number of Zld binding sites accelerates the kinetics of transcriptional activation regardless of their past transcriptional state. In spite of its known pioneering activities, we show that Zld is not a mitotic bookmarker and is neither necessary nor sufficient to foster mitotic memory. Fluorescent recovery after photo-bleaching and fluorescent correlation spectroscopy experiments reveal that, Zld is highly dynamic and exhibits transient binding to chromatin. We propose that Zld low binding rates could be compensated for by local accumulation of Zld in nuclear microenvironments in vivo, thus allowing rapid and coordinated gene activation.

developmental biology↗